Method and Apparatus for Elevator Hobble Compensation

ABSTRACT

A compensating hobbling assembly secures a set of elevators in a level position, while compensating for side or non-axial loading. An adjustable bail clamp is affixed to a bail, while an extendable hobble compensation assembly is pivotally attached to a set of elevators. A cable, chain or other flexible member having a finite length extends between the bail clamp and the hobble compensation assembly. Tension of said cable, chain or other flexible member can be adjusted so that the elevators are maintained in a substantially level position when suspended or hanging from bails. The hobble compensating assembly can extend, allowing the elevators to tilt and relative to the bails.

CROSS REFERENCES TO RELATED APPLICATION

Priority of U.S. Provisional Patent Application Ser. No. 61/715,910, filed Oct. 19, 2012, Incorporated herein by reference, is hereby claimed.

STATEMENTS AS TO THE RIGHTS TO THE INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

None

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to an elevator hobbling assembly for use with tubular running systems.

2. Brief Description of the Prior Art

Oil and gas operations frequently involve the use of pipe and/or other tubular goods manipulated from a surface drilling rig or other surface facility. Such tubular goods are usually inserted into a well in a number of separate sections of substantially equal length called “joints.” Such joints are typically screwed together or otherwise joined end-to-end at the rig floor of a drilling rig in order to form a substantially continuous “string” of pipe that reaches downward into the earth's crust. As the bottom or distal end of the pipe string extends further into a well, additional sections of pipe are added to the upper end of the pipe string at said drilling rig.

The process of installing a string of pipe in a well is typically commenced by lowering a first section of pipe into a wellbore at a drilling rig floor, and suspending said section of pipe in place using a lower gripping apparatus commonly referred to as “spider slips”. In this position, the uppermost end of said first section of pipe protrudes from the upper opening of a well and is generally situated a desired distance above the rig floor. Thereafter, a second section of pipe is lifted within a drilling rig derrick and suspended vertically within said derrick. Said second section of pipe is then positioned in linear alignment above the first section of pipe (which was previously run into the well and is being gripped by said spider slips); the lower end of said second pipe section can then be connected to the upper end of said first pipe section.

After said first and second sections of pipe have been joined together (typically using a threaded connection), a vertically movable upper gripping assembly, commonly referred to as a set of elevators, or simply “elevators”, can be lowered around the upper end of such joined pipe sections. Once said elevators are properly positioned, a gripping apparatus known as elevator slips can be latched around the external surface of the pipe in order to grip such pipe. Said elevators can then be raised, thereby lifting the pipe and taking weight off of the lower spider slips. In this configuration, the lower spider slips can then be disengaged, allowing the entire weight of the pipe string to be suspended from the elevator slips of said elevators.

After said spider slips have been raised, the joined sections of pipe (hanging from the elevator slips) can then be lowered into the well by lowering said elevators a desired distance before re-engaging the spider slips and disengaging said elevator slips. This process can be repeated until a desired length of pipe (i.e., the desired number of pipe sections) is inserted into the wellbore.

On most drilling rigs, elevators are suspended using a pair of elongate and substantially parallel linkage members commonly referred to as “bails”. Each bail generally comprises an upper and a lower loop with a rigid body or spacer member disposed between said upper and lower loops. The upper loop of each bail is typically connected to a rig's traveling block or vertically movable top drive unit, while the lower loop of each bail is secured to lifting ears of the elevators. This connection method typically allows such elevators to pivot about a substantially horizontal axis, created by the cooperating substantially parallel lower loops of the bails and the elevator lifting ears, while said elevators are suspended from the bails.

Conventional elevators are frequently prevented from unwanted pivotal movement using a process known as “hobbling” wherein the elevators are tied or otherwise secured to the bails using a chain or cable. Such chain or cable limits pivotal movement of the elevators and keeps the elevators substantially level (relative to a rig floor) while such elevators are suspended from the bails. In this manner, said elevators can latch on to a substantially vertical section of pipe within a derrick and/or protruding from the upper opening of a well bore.

Although generally acceptable for use on vertical wells, such conventional elevator hobbling systems are not desirable for use on directional wells including, without limitation, horizontal wells. As a length of pipe moves further into a non-vertical section of a well, the exposed portion of the pipe frequently “leans” such that it is not axially aligned with the drilling rig derrick (that is, it is no longer vertical relative to the drilling rig floor). Thus, as such pipe is raised or lowered into a well, the leaning of such pipe can place excessive loading on a hobble chain or cable which, in turn, can create an unsafe condition for nearby personnel.

Thus, there is a need for a system for safely hobbling a set of elevators hanging from bails in a drilling rig derrick. The hobbling system should limit pivotal movement of elevators prior to such elevators latching on to a section of pipe, while permitting limited pivotal movement after elevator slips are set and a pipe string is lowered into a well.

SUMMARY OF THE INVENTION

The present invention comprises a compensating hobbling assembly for securing elevators to bails using a chain or cable. The hobbling chain or cable limits pivotal movement of the elevators and keeps the elevators substantially level relative to a section of pipe to be gripped while such elevators are suspended from a set of bails. Further, because the hobbling assembly of the present invention is compensated, elevators are permitted to tilt in order to accommodate non-vertical or leaning pipe, as well as the non-linear loading caused by such pipe.

An adjustable bail clamp is secured to a bail, while an extendable hobble compensation assembly is pivotally attached to a set of elevators. A cable, chain or other flexible member having a finite length extends between said bail clamp and said hobble compensation assembly. Tension of said cable, chain or other flexible member can be adjusted by selectively setting the vertical position of said bail clamp on said bail. Said bail clamp can be positioned on said bail so that said elevators are maintained in a substantially level position when suspended or hanging from a pair of bails.

The hobble compensating assembly of the present invention permits a pipe section to be gripped by said elevators, even when such pipe section is not oriented purely vertically. In such instances, a non-vertical pipe section can impose unwanted or unsafe non-axial loading or other forces on a set of elevators. In order to account for such forces/loading, the hobble compensating assembly of the present invention can beneficially extend in a controlled manner, thereby allowing said elevators to tilt or partially rotate relative to said bails in response to such forces/loading.

BRIEF DESCRIPTION OF DRAWINGS/FIGURES

The foregoing summary, as well as any detailed description of the preferred embodiments, is better understood when read in conjunction with the drawings and figures contained herein. For the purpose of illustrating the invention, the drawings and figures show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed in such drawings or figures.

FIG. 1 depicts a side view of an unbalanced set of elevators hanging from a set of conventional bails.

FIG. 2 depicts a front view of a set of elevators suspended from conventional bails and equipped with a hobble assembly of the present invention gripping a section of pipe.

FIG. 3 depicts a side view of a set of elevators suspended from conventional bails and equipped with a hobble assembly of the present invention.

FIG. 4 depicts a side view of a set of elevators equipped with the hobble assembly of the present invention gripping a section of pipe.

FIG. 5 depicts a side perspective view of a bail clamp of the present invention.

FIG. 6 depicts a side partial sectional view of a hobble compensator assembly of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 depicts a side view of a set of unbalanced elevators 10 hanging from a pair of conventional bails 20. Each bail 20 of said pair generally comprises an upper loop (not shown in FIG. 1) and a lower loop 21, as well as a rigid spacer or member 22 positioned between said upper and lower loops. A substantially similar, if not identical, bail is disposed on the opposite side of elevators 10 and bail 20 depicted in FIG. 1, but is obscured from view and is not visible in FIG. 1.

Bail 20 is beneficially connected at its upper end to a rig's traveling block or vertically movable top drive unit, while lower loop 21 is secured to a lifting ear 11 of elevators 10. Lifting ear 11 of elevators 10 is generally free to rotate within lower loop 21 of bail 20. In this manner, elevators 10 are free to pivot about a substantially horizontal axis extending through cooperating lower loop 21 and elevator lifting ear 11.

As depicted in FIG. 1, elevator slips 12 of elevators 10 are shown in a raised, non-gripping position. As noted above, after sections of pipe have been joined together (typically using a threaded connection) and partially installed within a well, a portion of said pipe 100 can extend out of the upper opening of such well. Elevators 10 can then be lowered around the upper end of such pipe, typically by lowering said elevators over the upper end of such pipe section 100. Once elevators 20 are properly positioned relative to such pipe, elevator slips 12 of said elevators 10 can be engaged in order to grip the outer surface of said pipe 100. However, because of the geometry of elevator 10, the weight of elevator slips 12 is primarily concentrated near the rear portion 13 of elevators 10, particularly when said elevator slips 12 are in an unlatched or disengaged position as depicted in FIG. 1. This unbalanced condition causes elevators 10 to tilt, making it difficult, if not impossible, for such elevators 10 to be properly lowered over and receive the upper end of pipe section 100.

Conventional elevators are sometimes prevented from unwanted pivotal movement using a process known as “hobbling,” wherein said elevators are tied or otherwise secured to bails using a chain, cable or other similar device. The hobbling chain or cable limits pivotal movement of the elevators and keeps the elevators substantially level relative to a section of pipe to be gripped while such elevators are suspended from the bails. In this manner, said elevators can be lowered over a substantially vertical section of pipe within a drilling rig derrick and/or protruding from the upper opening of a well bore.

FIG. 2 depicts a front view of a set of elevators 10 suspended from a pair of conventional bails 20 and equipped with a hobble assembly 30 of the present invention gripping a section of pipe 100. Each bail 20 of said pair generally comprises an upper loop (not shown in FIG. 2) and a lower loop 21, as well as a rigid spacer or member 22 positioned between said upper and lower loops. Each bail 20 is beneficially connected at its upper end to a rig's traveling block or vertically movable top drive unit (not shown in FIG. 2), while each lower loop 21 is secured to a lifting ear 11 of elevators 10.

FIG. 3 depicts a side view of a set of elevators 10 suspended from a pair of conventional bails 20 and equipped with hobble assembly 30 of the present invention. In a preferred embodiment depicted in FIG. 3, hobble assembly 30 comprises hobble compensator assembly 40, bail clamp 50 and a connecting member having a finite length, such as cable 60. As discussed more fully below, hobble compensator assembly 40 is pivotally pinned or otherwise rotatably mounted to elevators 10, while bail clamp 50 is attached to bail 20 (typically on substantially cylindrical body member 22 of bail 20). Cable 60 connects said bail clamp 50 to hobble compensator assembly 40. It is to be observed that said connecting member can alternatively comprise a chain, wire rope or other device having desired flexibility and strength characteristics.

FIG. 4 depicts a side view of elevators 10 equipped with hobble assembly 30 of the present invention gripping pipe section 100. Elevator slips (not visible in FIG. 4) are in a “set” or engaged position; as such, said elevator slips are retracted within elevators 10 allowing said elevators 10 to grip the outer surface of pipe section 100. As depicted in FIG. 4, said pipe section 100 is tilted from vertical and is not oriented in linear alignment with the travel path of elevators 10. Such tilt of pipe section 100 increases non-axial loading on said elevators 10 which can create an unsafe condition for nearby personnel.

FIG. 5 depicts a side perspective view of bail clamp 50 of the present invention. In a preferred embodiment, bail clamp 50 comprises a pair of opposing semi-cylindrical members 51 and 52 that are hingedly attached to each other using hinge pin 53. A first substantially planar flange member 54 having a plurality of apertures 56 disposed there through extends from semi-cylindrical member 52. Similarly, a second substantially planar flange member 55 having a plurality of apertures 56 disposed there through extends from semi-cylindrical member 51. In a preferred embodiment, flange member 55 has sloped or tapered edges 59 defining apex section 57, as well as anchor hole 58 disposed near said apex section 57 and extending through said flange member 55.

In a preferred embodiment, opposing semi-cylindrical members 51 and 52 can be hingedly closed around the outer surface of a bail body member. In this position, substantially planar flange members 54 and 55 can be closed against each other in side-by-side relationship with bores 56 of each flange member being aligned. Bolts or other rigid fasteners can be used to secure said planar flange members 54 and 55 together. Anchor hole 58 provides a rigid anchor point for attaching a shackle or other similar anchoring device.

FIG. 6 depicts a side sectional view of hobble compensator assembly 40 of the present invention. As depicted in FIG. 6, hobble compensator assembly 40 comprises an outer housing 41 defining an inner void or chamber, and having housing base 48. Rod 42, having eye nut 45 at one end and spring base 43 at the opposite end, is slidably disposed within said inner chamber of housing 41; rod 42 can extend or retract relative to housing 41. Compression spring 44 is mounted within said inner chamber of housing 41 on spring base 43. End connection member 46 having bore 47 is disposed near housing base 48.

Referring back to FIG. 4, elevators 10 are equipped with hobble assembly 30 of the present invention; although not visible in FIG. 4, elevator slips 12 of elevators 10 are engaged and gripping pipe section 100. Bail clamp 50 is secured to body section 22 of a bail 20, while end connection member 46 of hobble compensation assembly 40 is pivotally mounted to the outer surface of elevators 10. Shackle 61 is rotatably connected to anchor hole 58 of flange member 55. Sloped edges 59 of said flange member 55 permit a wide range of rotation of said shackle 61 within said anchor hole. Similarly, shackle 62 is rotatably connected to eye nut 45 of hobble compensator assembly 40. Cable 60 having a finite length extends from shackle 61 to shackle 62 and is secured at each end to said shackles.

Tension of cable 60 can be adjusted by selectively setting the vertical position of bail clamp 50 on body member 22 of bail 20. In a preferred embodiment, said bail clamp 50 is positioned on bail 20 so that elevators 10 are maintained in a substantially level position without compression spring 44 (not visible in FIG. 4) of hobble compensator assembly 40 being compressed (even, for example, when elevator slips 12 are in an upward or disengaged position).

As depicted in FIG. 4, pipe section 100, which is gripped by elevators 10, is not in vertical orientation. As such, said pipe section 100 imposes forces on elevators 10 that are not aligned with the longitudinal axis of said pipe section 100. When such forces overcome the bias forces of compression spring 44, rod 42 of hobble compression assembly 40 can extend (while compression spring 44 contracts or compresses within housing 41), thereby allowing elevators 10 to tilt or rotate within lower loop 21 of bails 20.

After pipe section 100 has been lowered a desired distance into a well, a set of spider slips can be set in order to suspend the weight of the pipe string. At this point, slips (12) of elevators 10 can be released or disengaged from said pipe section 100, and said elevators 10 can be raised off the upper end of pipe section 100. With no pipe engaged within elevators 10, hobble assembly 30 returns elevators 10 to a substantially level orientation.

The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. 

What is claimed:
 1. An apparatus for hobbling elevators comprising: a) a clamp mounted to at least one bail; b) a compensating assembly mounted to said elevators; c) a connecting member having a first end, a second end and a fixed length, wherein said first end is connected to said clamp and said second member is connected to said compensating assembly.
 2. The apparatus of claim 1, wherein said connecting member comprises a cable.
 3. The apparatus of claim 1, wherein said connecting member comprises a chain.
 4. The apparatus of claim 1, wherein said compensating assembly comprises: a) a housing; b) a rod movably disposed in said housing; and c) a compression spring disposed around said rod and biasing said rod toward a retracted position.
 5. The apparatus of claim 1, wherein said clamp comprises: a) a first semi-cylindrical member having a first side and a second side; b) a flange member, having at least one aperture, extending from said first side of said first semi-cylindrical member; c) a second semi-cylindrical member having a first side and a second side, wherein said second side of said second semi-cylindrical member is hingedly attached to the second side of said first semi-cylindrical member; and d) a flange member, having at least one aperture, extending from said first side of said second semi-cylindrical member.
 6. The apparatus of claim 5, wherein at least one of said flange members has tapered surfaces defining an apex.
 7. The apparatus of claim 1, wherein said compensating assembly is rotatably mounted to said elevators.
 8. A method for hobbling elevators comprising: a) mounting a clamp to at least one bail; b) mounting a compensating assembly to said elevators; c) attaching a connecting member between said clamp and said compensating assembly.
 9. The method of claim 8, wherein said connecting member comprises a cable.
 10. The method of claim 8, wherein said connecting member comprises a chain.
 11. The method of claim 8, wherein said compensating assembly comprises: a) a housing; b) a rod movably disposed in said housing; and c) a compression spring disposed around said rod and biasing said rod toward a retracted position.
 12. The method of claim 8, wherein said clamp comprises: a) a first semi-cylindrical member having a first side and a second side; b) a flange member, having at least one aperture, extending from said first side of said first semi-cylindrical member; c) a second semi-cylindrical member having a first side and a second side, wherein said second side of said second semi-cylindrical member is hingedly attached to the second side of said first semi-cylindrical member; and d) a flange member, having at least one aperture, extending from said first side of said second semi-cylindrical member.
 13. The method of claim 12, wherein at least one of said flange members has tapered surfaces defining an apex. 